The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Lawn care, golf courses, sod farms, athletic fields and the like all require herbicide treatments to control weeds. It is an important aspect of the herbicidal treatment that it is able to control such weeds without harming the lawn or other turf in which the weeds are found. An important consideration in treating turf is the cost, in terms of man and machine hours, cost of chemicals, and down-time of the treated surface for a variety of normal uses. Therefore, there is considerable pressure to combine various lawn treatments, including treating diseases, eliminating pests, fertilizing, and treating for weeds.
Crabgrass is a huge problem in turf. It will aid in an understanding of the present invention for those not skilled in the art, to know that the life cycle of grassy weeds occurs in stages which are very well known to those skilled in the art. There is of course the pregermination stage. After germination has begun there is a post germination stage. When the plant rises from the ground it first appears as a shoot and develops leaves. The leaf stage may be characterized by the number of leaves, e.g. 1 leaf stage, 2 leaf stage etc., and is generally characterized as leaves extending from a single shoot or stalk. As the plant matures, tillers develop which are branching, sprouts or stalks that will generally eventually develop leaves of their own. This stage of the weed growth may be characterized by the number of tillers present, such as the 1 tiller stage, the 2 tiller stage, etc. Thus, stages may be referred to for example as “the preemergence stage”, the “early post germination 1-2 leaf stage”, the “untillered 3-5 leaf stage” and the “tillered” stage which may further be defined as for example, as the “1 tiller stage”, the “2 tiller stage”, the “3+ tiller stage” and the like.
In order to control grassy weeds in lawn or turf it is known to treat such grassy weeds with preemergent herbicides. For example, with regard to grassy weeds such as crabgrass, goosegrass or other grassy weeds, it is known to treat a lawn, golf course, sod farm, athletic field or other lawn or turf setting infested with the grassy weeds early in a growing season before the grassy weed has germinated with a preemergent herbicide such as prodiamine. The use of prodiamine to control crabgrass in turf is well known. However, crabgrass continually re-seeds, so it is not possible to effectively treat established crabgrass using only prodiamine.
Fenoxaprop p-ethyl (we herein alternatively refer to the herbicide as “fenoxaprop”) is a postemergence graminicide used on cool-season turfgrasses to control crabgrass and other annual grass weeds. It is available as the D isomer, the R isomer, or as mixtures. The R isomer is recognized as being more effective in some situations, and in preferred embodiments of this invention the active isomer is present and the less active isomer is only present in trace quantities. It is known to treat grassy weeds such as crabgrass, goosegrass or other grassy weeds after the weed has emerged in the lawn, golf course, sod farm athletic field or other lawn or turf setting, with a post emergent herbicide such as fenoxaprop.
There is considerable art suggesting combinations of fenoxaprop with other herbicides results in reduced fenoxaprop efficacy. See, for example, Antagonism of Fenoxaprop by Broadleaf Herbicides (Harrison, 1987), stating that the herbicidal action of fenoxaprop is significantly reduced when applied within several days of or in combination with various postemergence broadleaf herbicides, resulting in unacceptable levels of grassy weed control. See also Fenoxaprop Activity Influenced by Auxin-like Herbicide Application Timing (Dernoeden and Fidanza, HortScience 29 (12), 1994), stating smooth crabgrass control by fenoxaprop was reduced significantly when the broadleaf weed herbicide was applied up to 14 days or less before fenoxaprop was applied.
That said, it is also known to combine post-emergent fenoxaprop with various pre-emergent herbicides to achieve enhanced control of crabgrass. See, for example, Fenoxaprop Combined with Preemergence Herbicides for Crabgrass and Goosegrass Control in Turf (Dernoeden, HortScience 23 (1), 1988). which noted when fenoxaprop was applied in combination with bensulide, beefin, DCPA, oxadiazon, pendimethalin, or prodiamine, excellent (90% to 100%) season-long smooth crabgrass control was achieved. In this work, fenoxaprop and prodiamine were tank mixed or applied separately, at rates of 0.28 and 0.39 kg/ha fenoxaprop plus 1.1 kg/ha prodiamine. The combination treatments provided greater crabgrass control than did treating with fenoxaprop alone at identical application rates.
This enhanced control provided by applications of prodiamine and fenoxyprop is known in the industry. Labels commonly suggest using lawn treatments of prodiamine and fenoxyprop. For example, the label for ACCLAIM™ EXTRA brand fenoxaprop states Acclaim Extra is useful at rates of 9.0 to 28 fluid ounces/acre . . . when tank mixing with the following products: Barricade®, bensulide 4E, Dacthal®, Dimension®, pendimethalin, Tupersan® and Ronstar® WP. Barricade® is a prodiamine formulation.
There are co-formulations of fenoxyprop and pendimethalin. AGR40500 3.09EC contains 1 part fenoxyprop p-ethyl to 34 parts pendimethalin. Testing of this formulation is described in Crabgrass Control With a Fenoxaprop/Pendimethalin Co-Formulation—1995 Results (J. Thomas and D. Spak, p 122), which found no significant difference in treatments with a 1:25 co-formulation versus the available 1:34 fenoxyprop/pendimethalin ratio.
Despite the common practice in the industry of when drafting patent applications, stating a new herbicide can be used with large random lists of herbicides, there are no commercially available formulations of prodiamine with fenoxaprop. Prodiamine is very difficult to formulate into emulsifiable concentrates, and the presence of other herbicides typically results in unstable formulations. It is known to mix solid prodiamine formulations with certain other herbiocides. US 20120108429 describes a granule having a surface and a core; a dicarboximide herbicide such as flumioxazin adhered to the surface or mixed into the core, and a dinitroaniline herbicide such as is trifluralin or prodiamine adhered to the surface or mixed into the core. In described embodiments the granules contained 0.125% total weight percent of flumioxazin, prodiamine, or trifluralin. And one reference, US 20100279865, taught a herbicidal composition comprising a mixture of glyphosate, diquat, prodiamine, and ammonium sulfate. In these formulations, 0.125% prodiamine is dissolved into iso-paraffins, and then admixed into a slurry containing surfactants and ammonium sulfate.
Emulsifiable concentrate (EC) formulations are a favored liquid delivery system for agriculturally active compounds. Conventional EC's contain one or more active ingredients dissolved in a water immiscible solvent together with emulsifying surfactants. These solvents typically have very low solubility in water and have a high solubility for most agriculturally active compounds.
The presence of the solvent imparts significant advantages to the formulation, such as a higher degree of systemicity, which leads to higher overall biological activity as compared to other commonly used agricultural formulations such as wettable powders (WP), water dispersible granules (WDG) or suspension concentrates (SC). Such EC's are further easier to transport and store.
Some major differential properties that lead to the better efficacy, stability and easier commercial use for EC's versus SC's may be described as; EC's are true solutions vs SC's which are suspensions, EC's are thermodynamically stable vs kinetically stable SC's, EC's have a much smaller particle size (<1 nm vs 2-5 um), the primary stabilization force for EC's is solution energy which is much greater than electrostatic and steric energy for SC's, and the lower intrinsic viscosity of EC's leads to Newtonian flow which is a key factor in non-clogging and even spread of herbicide during commercial sprayings.
A good EC is not made using a simple formula that is transferable from active ingredient to active ingredient. It requires the formation of a stable emulsion upon dilution with water that does not separate upon standing.
Several publications describe the development of herbicidal emulsifiable concentrates. More specifically towards the embodiments in the present invention, select publications have attempted to form or improve the emulsion properties of low solubility herbicides such as the dinitroaniline class of compounds, in which Prodiamine can be loosely placed. For example, WO 98/48624 shows the improvement of the stability of the EC emulsion by the use of a high amount of a water-insoluble C6-C18 alkyl pyrrolidone. However, these compounds are highly corrosive, have significant phytotoxicity and are too expensive for use in many agricultural applications. U.S. Pat. No. 5,035,741 shows the use of fatty acids in the formulation of emulsifiable concentrates to improve the herbicidal activity of some compounds. U.S. Pat. No. 5,270,286 describes the formulation of a combination of imidazolinone and dinitroaniline herbicides as emulsifiable concentrates with the use of aromatic solvents and alkyl phenol polyethylene oxide condensates to improve solubility. US 20100279865 describes the formulation of a combination of many herbicides with Prodiamine in which ammonium sulfate is used to stabilize the colloidal solution and an oil soluble solvent is specifically excluded, due to the solubilization difficulties inherent in these molecules. US 2011281731 describes the formation of an emulsifiable concentrate of dinitroaniline herbicides that avoids crystallization at low temperature and which comprises a diester co-solvent having the following formula R1OOC—(CH2)n-COOR2. US 2005113253 and JP7109193 describe fertilizer compositions that contain Prodiamine but specifically do not describe the potential use of an EC formulation to achieve a superior composition.
These and other publications in the prior art, describe the inherent difficulty in producing a commercially viable EC formulation and may be instructive for the absence of a commercial EC formulation containing Prodiamine herbicide as the primary active ingredient. Further, none of the above publications provides for a method to produce a stable, low phytotoxic, environmentally friendly emulsifiable concentrate formulation of Prodiamine, which can be used, directly or indirectly, for superior weed control.
Despite the desirability of applying fenoxaprop with prodiamine, there is no combination fenoxaprop/prodiamine emulsifiable concentrate on the market. Even recent work on the combination, for example US 20090005249 which was directed toward a combination of fenoxaprop and prodiamine, tank-mixed separate concentrates. US 20090005249 teaches “the fenoxaprop and the prodiamine may be mixed by admixing liquid solutions of the two, by admixing separate granules of the two and/or by providing granules which include both prodiamine and fenoxaprop on or impregnated within the granule.” When using three herbicides, the application states “the fenoxaprop, the prodiamine and the three-way herbicidal may be mixed by admixing liquid solutions of the three, by admixing separate granules of the three and/or by providing granules which include all three of prodiamine, fenoxaprop and the three-way herbicidal composition on or impregnated within the granule.”
While US 20090005249 does teach that fenoxaprop and prodiamine may be both present in a granule, it does not teach a liquid concentrate comprising both. For formulating the liquid solutions, both the text and the examples teach tank mixing—the same art that was used in the 1985 studies.
What is needed is an emulsifiable concentrate solution containing fenoxaprop and prodiamine.